JPH0789325A - Hollow stabilizer - Google Patents

Abstract

PURPOSE:To hollow a stabilizer for a truck or bus by forming a material of an alloy steel pipe containing chromium and molybdenum for reducing the weight of a vehicle, and by quenching it and then tempering it so as to be within a range of a prescribed hardness. CONSTITUTION:A hollow stabilizer for a large-size truck or bus is manufactured making a material of a chromium-molybdenum steel pipe whose compositions are 0.28 to 0.33% carbon, 0.15 to 0.35% silicon, 0.40 to 0.60% manganese, 0.35% or less phosphorus, 0.040% or less sulfur, 0.80 to 1.10% chromium, 0.15 to 0.25% molybdenum by weight, and the remainer are iron and inevitable impurities; and it is quenched at 920 deg.C, and tempered at 370 deg.C for obtaining a quenching hardness of 2HRC 40 or more. In the case of a hollow stabilizer for a large-size truck or bus, the weight reduction ratio is 30%, and the manufacturing cost thereof is lower than that of a solid product. It is obvious that its life is sufficiently long, and it is excellently used for a large-size truck or bus.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stabilizer used as a member of a shock absorber, and more particularly to a hollow stabilizer for an automobile.

[0002]

2. Description of the Related Art Conventional stabilizers generally use spring steel as a steel type from the viewpoint of having the same spring action as a spring. In addition, the size of the stabilizer itself is decided first by the layout design,
Once the spring constant is determined, the material diameter and stress are also determined, and spring steel with good hardenability has been mainly used. However, in recent years, there has been an increasing need to reduce the weight of vehicles due to measures against waste gas, and steel pipes have been increasingly used for stabilizers that have been solid until now. In particular, passenger cars have become quite popular due to the use of low-cost steel (STKM13 composition with boron added).

However, in the case of trucks and buses, the rigidity of the stabilizer is required to be considerably higher than that of passenger cars. Therefore, when using steel pipes, it is necessary to use small-diameter and thick-wall pipes. What is commercially available as such a material is a so-called seamless steel pipe, but this is expensive and the material quality is not sufficient. Further, since a steel pipe with good hardenability cannot be obtained, it is the actual situation that a heavy solid stabilizer is usually used. Further, the reason why the hollowing of the stabilizer is not widespread in passenger cars is that the concept of the suspension of the truck is different from that of passenger cars, and the stabilizer is attached only when an order is placed.

However, with the shift to high-speed, long-distance running of trucks as well, ride comfort and maneuverability similar to those of passenger cars are required, and stabilizers have been standardly installed by separating the functions of suspensions. Also in the case of buses, stabilizers are generally used because air suspension has become widespread. Furthermore, by improving the technology for manufacturing steel pipes, it has become possible to reduce the diameter and thickness of electric resistance welded pipes, which are superior to seamless pipes in terms of price and quality, so it has been attempted to make stabilizers for truck buses hollow. However, not all problems have been resolved.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been made to find a new steel material having properties suitable as a stabilizer, and to provide a hollow stabilizer having properties not heretofore obtained.

[0006]

The structure of the present invention for solving the above problems is a hollow stabilizer as set forth in the claims. That is, it is a hollow stabilizer obtained by forming an alloy steel pipe containing chromium and molybdenum into a predetermined shape using a raw material and having a hardness of H _R C 40 or more. And, the composition of the alloy steel containing chromium and molybdenum is expressed by weight%: carbon 0.28 to 0.33, silicon 0.15 to 0.35, manganese 0.40 to 0.60, phosphorus 0.035. Hereinafter, sulfur is 0.040 or less, chromium is 0.80 to 1.10, molybdenum is 0.15 to 0.25, and the balance is iron and inevitable impurities. The action of each component of the above alloy steel will be described below. C is an element necessary to secure hardness after heat treatment and to obtain strength and toughness, and if it is less than 0.28%, the above properties as a stabilizer cannot be obtained,
If it exceeds 0.33%, the toughness and fatigue strength after heat treatment will decrease, so the range was made 0.28 to 0.33%.

Si is required to be 0.15% or more as a deoxidizing agent at the time of melting, and if it exceeds 0.35%, the fatigue strength decreases, so the range is 0.15 to 0.35%. Mn is required to be 0.40% or more in order to obtain a deoxidizer and hardness during melting, and if it exceeds 0.60%, toughness is lowered, so it is less than 0.1%.
The range was 40 to 0.60%. Cr is an element effective for improving the hardness due to hardenability, and if less than 0.80%, these effects cannot be sufficiently expected, and 1.10%
%, The toughness decreases, so the range was made 0.80 to 1.10%.

Mo is an element necessary for obtaining the strength, toughness and hardness due to the hardenability of steel. If it is less than 0.15%, these effects cannot be expected sufficiently, and if it exceeds 0.25%, it becomes coarse. 0.15 to 0.15 because carbides are easily precipitated and the toughness is deteriorated.
The range is 0.25%. In order to manufacture a hollow stabilizer using an alloy steel pipe having the above composition as a raw material, this steel pipe is formed into a predetermined shape, then quenched and tempered to a predetermined hardness range. When manufacturing a hollow stabilizer for trucks and buses, it is suitable to use a steel pipe having an outer diameter of 34 to 65 mm and a wall thickness of 6 to 12 mm.

[0009]

EXAMPLES The present invention will be specifically described below with reference to examples. Example 1 C: 0.31%, Si: 0.24%, Mn: 0.58
%, P: 0.023%, S: 0.005%, Cr: 0.
A chromium-molybdenum steel material containing 92% and Mo: 0.17% was tested for hardenability by the Jominy test method.
The result is shown in FIG. J ₄₀ = 12 mm.

Comparative Example 1 C: 0.25%, Si: 0.20%, Mn: 0.45
%, P: 0.020%, S: 0.015%, Cr: 0.
Hardenability was tested when a boron steel material containing 30% and B: 0.003% was heat-treated under the following conditions. The result is shown in FIG. J ₄₀ = 6 mm.

Example 2 C: 0.30%, Si: 0.24%, Mn: 0.49
%, P: 0.012%, S: 0.003%, Cr: 0.
A product when a hollow stabilizer for large trucks with the shape shown in Fig. 2 was made from a chromium / molybdenum steel tube containing 9% and Mo: 0.16%, and was quenched at 920 ° C and tempered at 370 ° C. The results of measuring the hardness of the cross section of are shown in FIGS. FIG. 3 shows the tested site and FIG.
Is a detailed view of the measurement of the quenching hardness of the cross section, and FIG. 5 is a detailed view of the measurement of the tempering hardness of the cross section. From this result, it is understood that the quenching hardness T ₂ HRC of 40 or more can be achieved. Furthermore, in the case of a large-sized truck hollow stabilizer, the weight reduction rate was 30% and the manufacturing cost was lower than the solid product.

Example 3 A conventional spring steel (SU) having the same spring characteristics as the hollow stabilizer made of the chromium-molybdenum steel pipe of Example 2 is used.
Fig. 6 shows the result of the labor test of the solid stabilizer manufactured in P9). It can be seen that the hollow stabilizer of the present invention has a working strength equivalent to that of the solid stabilizer of SUP9 spring steel.

[0013]

As described above, it is apparent that the hollow stabilizer of the present invention has a particularly high weight reduction rate and a sufficiently long life. Especially, it is excellent as a stabilizer for large trucks and buses.

[Brief description of drawings]

FIG. 1 is a graph showing a Jominy curve of a steel material used in a product of the present invention and a conventional product,

FIG. 2 is a partially cut plan view (a) and a side view (b) showing a specific shape of a product of the present invention,

FIG. 3 is a schematic diagram showing test sites of the product of the present invention,

FIG. 4 is a detailed view showing the quenching hardness of the cross section of the product of the present invention,

FIG. 5 is a detailed view showing the tempering hardness of the cross section of the product of the present invention,

FIG. 6 is an S- showing the durability of the product of the present invention and the conventional product.
N diagram.

Claims (2)

[Claims] 1. A obtained by forming an alloy steel containing chromium and molybdenum in a predetermined shape, a hollow stabilizer, characterized in that the quenching hardness is H _R C40 or higher. 2. When the composition is expressed by weight%, carbon 0.28 to 0.33 silicon 0.15 to 0.35 manganese 0.40 to 0.60 phosphorus 0.035 or less sulfur 0.040 or less chromium 0.80 ˜1.10 Molybdenum 0.15 to 0.25, the balance being iron and inevitable impurities, The hollow stabilizer according to claim 1.